Our preliminary results show that Fourier Transform Infrared Difference Spectroscopy can be used to study the state of the chromophore (retinal) and protein conformation in bacteriorhodopsin and its photocycle intermediates. We propose a three year research project to investigate both bacteriorhodopsin and visual pigments in the infrared region. Retinal analogs incorporated into the protein will be studied to provide information for the assignment of the infrared absorption bands and the nature of the processes that follow the absorption of light. Fourier Transform Infrared Difference Spectroscopy will also permit us to follow the kinetics of these systems at low temperatures. The extension of these studies to shorter times (10 Mus) will be done with suitable modifications on our existing diode laser system. Experiments in the visible region using a flash photolysis system and spectrophotometer will be carried out both as a control and to allow correlation of our infrared results with existing resonance Raman and visible data. These results combined with the theoretical calculations of our collaborators, should provide important information on the proton pumping mechanism of bacteriorhodopsin and the early processes in visual excitation.